A touch screen which is an input medium is the most simple, convenient and natural human-machine interaction means at present. Thus touch screens have been increasingly applied to various electronic products, e.g., a mobile phone, a notebook computer, an MP3/MP4, etc.
FIG. 1 is a touch control liquid crystal display device in the prior art, and as illustrated, the touch control liquid crystal display device includes a substrate 2, a color film substrate 1, and a liquid crystal layer 3 arranged between the array substrate 2 and the color film substrate 1, and further includes a touch control layer 4 arranged between the liquid crystal layer 3 and the color film substrate 1. The touch control liquid crystal display device includes a plurality of pixel elements, all of which can control liquid crystals in their regions separately to be deflexed and further control a transmittivity of rays to thereby form a brightness-and-darkness variable display.
The touch control layer 4 is a multi-layer structure including a drive electrode layer 0041, a sense electrode layer 0042, and an insulation layer arranged between the drive electrode layer 0041 and the sense electrode layer 0042. FIG. 2 illustrates a structure of the drive electrode layer and the sense electrode layer, where the drive electrode layer 0041 includes a plurality of diamond-shaped drive electrodes 00410 extending in the Y direction and connected with each other to form drive lines, each of which is connected respectively to an external signal 00411; and the sense electrode layer 0042 includes a plurality of diamond-shaped sense electrodes 00420 extending in the X direction and connected with each other through metal bridges to form sense lines, each of is connected respectively to an external signal 00422. Gaps are arranged between the respective drive electrodes 00410 and sense electrodes 00420 insulated from each other.
In the existing touch control liquid display device, the size and the shape of the drive electrodes 00410 and the sense electrodes 00420 do not agree with those of the pixel elements, so some pixel elements correspond to the drive electrodes 00410 or the sense electrodes 00402, and some pixel elements correspond to the gaps between the drive electrodes 00410 and the sense electrodes 00420. Typically the drive electrodes 00410 and the sense electrodes 00420 are electrodes formed of a transparent electrically-conductive material, e.g., a film thin of indium tin oxide (ITO), thus influencing the transmittivity of rays to some extent, so that the transmittivity of the pixel elements corresponding to the drive electrodes 00410 or the sense electrodes 00420 may not agree with the transmittivity of the pixel elements corresponding to the gaps, thus resulting in uniformity of a display.
In the meantime, in the touch control liquid crystal display device in the prior art, all the drive electrodes or the sense electrodes will overlap with pixel electrodes, data lines and scan lines on the array substrate 2, and capacitances will be formed in their overlapping sections. FIG. 3 is an equivalent circuit of the traditional touch control liquid crystal display device, and as illustrated in FIG. 3, the alternating current drive power supply 101 is connected to the drive line 102, the drive line 102 with a specific length is equivalent to a resistance, and the drive electrode and the sense electrode form a mutual capacitance 103 at their intersection, and when there is a touch, the value of the mutual capacitance 103 will vary. Moreover the drive electrode and the sense electrode will also form a parasitic capacitance 105 respectively with another electrically conductive layer.
In a detection scheme of the traditional mutual capacitive touch screen, each drive line 102 is scanned sequentially, that is, a drive voltage 101 is applied sequentially to each drive line 102 while the remaining drive lines are grounded, and each sense line 104 is connected at a detection terminal to a detection unit 106, thereby detecting a signal on each sense line 104. Since a finger is a conductor, the mutual capacitance 103 at the location of a touch will vary due to a capacitive inductive effect of the finger when the finger touches the surface of the touch screen. This variation can be detected by the detection unit 106 to thereby judge whether and where there is a touch by the finger.
A drive signal may be seriously distorted when the parasitic capacitance 105 is very large. Distortion of the drive pulse will have an adverse influence upon a detection signal in the following two aspects that firstly the detection signal will be seriously attenuated and secondly if a touch signal is detected by acquiring charges, then distortion of the drive pulse will have the acquired charges varied all the time, thus making it difficult to detect; and this distortion will have a more serious influence upon a Fringe Field Switching (FFS) or In Plane Switching (IPS)-type liquid crystal screen. Since FFS and IPS is very sensitive to a variation or non-uniformity of an electric field, in the touch control liquid crystal display device in the prior art, drive electrodes or sense electrodes are arranged in correspondence to an area of some pixel elements while gaps between the drive electrodes or the sense electrodes correspond to an area of some pixel elements, and there are different strengths of the electric field at the locations of the electrodes and the gaps, thus influencing rotation of liquid crystal molecules and further having them deviate from a predetermined deflection angle to result in distortion which can be referred to noise of the touch control layer.
In the touch control liquid crystal display device, the pixel electrodes, the data lines, the scan lines and other electrically conductive layers on the touch control layer and the array substrate are at a short distance, so there is a large parasitic capacitance which hinders the touch signal from being detected. Moreover the touch control liquid crystal display device has to let light transmitted, so the touch control layer has to be of a light-transmitting material, e.g., a film thin of indium tin oxide (ITO), as described above, but the resistivity of the film thin of ITO is far larger than general metal so that there is a very large resistance of the touch control layer, thus lowering the sensitivity of detection by the touch control layer and increasing a load of the touch control layer. Consequently it is desired to address the problems of lowering the resistance and the parasitic capacitance, increasing the transmittivity and improving a display effect in the touch control liquid crystal display device.